{foreach elem in arr1 index idx}
{$elem} - {$idx % 2}
{/foreach}

{for i = 0 to b*4}{if i >= 4},{/if} {$i}{/for}

{$arr1[1]}
{$ arr1[1]
	.length}
{$a+b-1}
{$ a*(b/1) / 2-a+b+3/2  }

{if a}a!!!{/if}
{if b==null}b is not set{/if}

Hello {$2+a},
{if a+(b+1)/2*4 == 42/3}
conditional expression
{/if}

Best regards,
Support team